2011 End-of-the-Year Card

« 2010

Hypotrochoids are the types of patterns that are producted by Spirographs. A computer program generates a unique design for each card by choosing random values for the constants of the hypotrochoid equation. The resulting curves are drawn using a pen plotter.

Envelope and unfolded cards: envelope card 1 card 2

Card detail: detail

Stack of finished cards: stack of cards

The plotter in action:

Technical notes:

The hypotrochoid pattern was generated by a custom Python script. The paths were cut and culled using a combination of Inkscape and Illustrator. (Neither tool works well enough to do the job on its own.) The resulting file is converted to HPGL and sent to an HP 7475A plotter.

The typeface used for the card and envelope is Sentinel. The card is drawn using Rapidograph pens on Xerox Digital Color Elite Silk 110lb paper. The envelopes are laser printed on French Paper Company Newsprint Aged Dur-O-Tone.

« 2010

Related Pages

Eggbot
This card was partly inspired by a friend's (hi Sha!) Eggbot.
Ministry of Type: Guilloches
An article I came across a few years ago on hypotrochoids.
Getting an HP plotter to work under Linux
Includes a serial null modem cable pinout.
HP 7475A Interfacing and Programming Manual
I read way more of this than I had wanted to.